The Love Dare, the book that began as a plot device for the faith-based movie Fireproof, has become a New York Times Best Seller and a top-selling book on Amazon.com.

"This is the fastest-selling book we've ever handled," John Thompson, vice president of marketing for the B&H Publishing Group, said in an announcement.

"In America, the average book sells about 5,000 copies," he noted.

But even weeks before The Love Dare hit bookstores to coincide with the theatrical premiere of Fireproof on Sept. 26, more than 300,000 copies of the pro-marriage book had already been sold.

At that time, it was just hitting its third round of printing. Now, its in its seventh round.

The Love Dare is No. 1 on The New York Times Paperback Advice Bestsellers. It is ranked No. 1 on Amazon's top-selling Christian books and ranked 10th on Amazon's overall top-selling books.

Before its widespread demand, the book was merely a plot device in the surprise-hit Christian movie, Fireproof.

In the film, fireman Caleb Holt (played by Kirk Cameron) is asked by his father to take a 40-day marriage challenge before divorcing his wife, Catherine (played by Erin Bethea).

The challenge is presented in the form of a book, The Love Dare, which Holt agrees to read and which eventually transforms him and his view of love, marriage, and faith.

According to Provident Films, the movie's promoters, pre-screenings for Fireproof left audiences asking, "How can I get the book?"

In response, brothers and associate pastors Alex and Stephen Kendrick, who together directed and produced Fireproof and penned The Love Dare, made the effort to release the book with the film's opening.

"We shut out the world and wrote for several weeks," Stephen Kendrick said in a statement. "We weren't expecting such demand so early."

The Love Dare is a book that helps readers learn each day about the nature of love and then offers a "dare" to help implement that characteristic into their marriage.

With viewers seeing the power of love and reconciliation in Fireproof, couples now want to take the challenge too.

"To see Fireproof is to want the book, The Love Dare," Thompson with B&H Publishing Group said. "At the same time, for readers, this powerful little book stands alone in opening new understanding -- and new relationships."

The Kendricks and Sherwood Baptist Church have received hundreds of e-mails and letters from people all over the country responding to the message in Fireproof and The Love Dare.

Many feel new life has been breathed into their failing marriages, while others say it energizes the most important relationship in their lives.

In fact, promoters of the book have created a Web site, www.sharethelovedare.com, where individuals are journaling their experiences as they take the "dare."

Fireproof has already grossed more than $17.5 million and has been in the top 10 for the third straight week.

Sources: Lovell-Fairchild Communications, B&H Publishing Group, The Christian Post, Amazon.com, The New York Times Best Sellers List